The critical insight behind safety recovery is to introduce an additional policy that recovers potential unsafe states. In SafeRL-Kit, the representative model-free method is Recovery RL [1]}. We first learn a safe critic to estimate the future probability of constraint violation as
\(Q^\pi _\text{risk}(s_t,a_t) = c_t + (1-c_t) \gamma \mathbb {E}_{\pi } Q^\pi _\text{risk}(s_{t+1},a_{t+1}).\) 
